我照着网上的代码打 系统提示我错误(提示说:无法在空对象引用上启动活动组件信息)代码如下:
package com.example.fragementtest;import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;public class MainActivity extends AppCompatActivity { Button btn1; Button btn2; Intent a,b; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); btn1 = findViewById(R.id.button1); btn1.setOnClickListener(new BL()); btn2 = findViewById(R.id.button2); btn2.setOnClickListener(new BL()); replaceFragment(new RightFra()); } private class BL implements View.OnClickListener{ public void onClick(View v) { switch (v.getId()){ case R.id.button1: a = new Intent(MainActivity.this,Another.class); startActivity(a); break; case R.id.button2: b = new Intent(MainActivity.this,RightFra.class); startActivity(b); break; default: break; } } } private void replaceFragment(Fragment fragment){ FragmentManager fragmentManager = getSupportFragmentManager(); FragmentTransaction transaction = fragmentManager.beginTransaction(); transaction.replace(R.id.right_layout,fragment); transaction.commit(); }
}哪位大神可以指导一下我,看看这个代码错在哪里,怎么修改
package com.example.fragementtest;import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;public class MainActivity extends AppCompatActivity { Button btn1; Button btn2; Intent a,b; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); btn1 = findViewById(R.id.button1); btn1.setOnClickListener(new BL()); btn2 = findViewById(R.id.button2); btn2.setOnClickListener(new BL()); replaceFragment(new RightFra()); } private class BL implements View.OnClickListener{ public void onClick(View v) { switch (v.getId()){ case R.id.button1: a = new Intent(MainActivity.this,Another.class); startActivity(a); break; case R.id.button2: b = new Intent(MainActivity.this,RightFra.class); startActivity(b); break; default: break; } } } private void replaceFragment(Fragment fragment){ FragmentManager fragmentManager = getSupportFragmentManager(); FragmentTransaction transaction = fragmentManager.beginTransaction(); transaction.replace(R.id.right_layout,fragment); transaction.commit(); }
}哪位大神可以指导一下我,看看这个代码错在哪里,怎么修改
解决方案 »
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2. 看错误描述,是intent为Null。
3. 另外,你的代码是不是应该格式化一下?